It depends on which cell tower picks up the signal. Your call may not always be routed to the nearest 9-1-1 Center. The Antioch Police Department, working in cooperation with several of the Wireless Service Providers, have made improvements to the wireless 9-1-1 services by directing more than half of the cell towers located in the city to the Antioch Police Department instead of the California Highway Patrol (CHP). The remaining cell towers of these Wireless Service Providers have sectors that cover State Route Highway 4, and therefore are required to direct wireless 9-1-1 calls to CHP.
